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Michael Phelps, Missy Franklin and Katie Ledecky had an amazing day for USA swimming, capturing gold in the 100m butterfly, the 200m backstroke and the 800m freestyle.

Updated at 6:25 AM EDT on Saturday, Aug 4, 2012

The U.S. swimming team won three golds during a stunning streak Friday, with Michael Phelps taking home his 21st medal, Missy Franklin setting a new world record, and 15-year-old Katie Ledecky winning the 800m freestyle.

Franklin won the gold in the 200m backstroke with a world-record pace and became the first American woman in 40 years to win gold in the event, her signature race.

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Phelps followed up by taking gold in the 100m butterfly for another record -- going out on his last individual event of the London Games with his 21st career medal. He also became the second Olympic athlete in history to win two individual events at three consecutive Olympics.

And Ledecky, the youngest swimmer on Team USA, won the 800m freestyle with a time of 8:14.63.

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All in all it was a remarkable day for Americans in the pool.

Franklin, 17, notched her world record with a time of 2:04.06. Anastasia Zueva of Russia took the silver and American Elizabeth Beisel won bronze. Franklin now has three golds and a bronze in London.

"I can't believe what just happened," she told The Associated Press after the race. "In that last 25, I knew I was giving it everything I had because I couldn't feel my arms and legs and I was just trying to get my hand to the wall as fast I could."

Franklin had swum 13 races in six days leading up to the 200m backstroke. She'll return to the pool once more on Saturday for the women's 4x100m medley relay.

Phelps won his 17th career gold medal in the 100m butterfly with a time of 51.21. He was next-to-last when he touched the wall for the first 50 meters then rallied for the first-place finish. South African Chad le Clos took silver with a time of 51.44. Russia's Evgeny Korotyshkin won bronze in 51.44.

"I'm just happy that the last one was a win," Phelps told the AP. "That's all I really wanted coming into the night."

The race came on the heels of Phelps' history-making three-peat win in the 200m individual medley Thursday over long-time rival Ryan Lochte. He is expected to finish his Olympic career Saturday with the men's 4x100m medley relay.

"He's the king of the Olympics Games," said his butterfly rival, Serbia's Milorad Cavic.

Ledecky, the teen swimming sensation from Bethesda, Md., bested her closest competitor, Spain's Mireia Garcia Belmonte, by over four seconds. Team GB's Rebecca Adlington took bronze. Ledecky became the youngest woman ever to win the 800m freestyle and her final time was the second-fastest in history.

American Cullen Jones later took silver in the men's 50m freestyle. Florent Manaudou of France won the gold and world champion Cesar Cielo of Brazil took bronze.